A synchronous reluctance type rotary electric machine includes a rotor and a stator. The rotor includes a shaft rotatably supported and extending in an axial direction at a center of a rotation axis and a rotor core externally fitted and fixed to the shaft. The stator includes a stator core disposed on an outer circumference of the rotor core to be spaced apart from the rotor core and having a plurality of teeth disposed at intervals in a circumferential direction and multipole multiphase armature windings respectively wound around the plurality of teeth.
Multi-layered hollow parts having a convex shape toward a radially inward side are formed for each pole in the rotor core. When the hollow parts are formed in this manner, a direction in which magnetic flux easily flows and a direction in which magnetic flux does not easily flow are formed in the rotor core. Thus, the synchronous reluctance type rotary electric machine rotates the shaft using a reluctance torque generated by the hollow parts.
Here, in order to improve a rotational torque of the shaft, it is desirable to cause magnetic flux flowing through the rotor core to flow to the shaft side (a radial center side of the rotor core) as much as possible and distribute the magnetic flux uniformly over the entire rotor core. For this reason, for example, an interval between two hollow parts of the rotor core is set to be larger as the interval is closer to the shaft so that magnetic saturation does not occur at a portion close to the shaft in many cases.
In practice, however, magnetic flux flowing through the rotor core decreases in magnetic flux density as the magnetic flux moves closer to the shaft (closer to the radial center). Therefore, even when an interval between two hollow parts of the rotor core is set to be larger as the interval becomes closer to the shaft, there is a possibility that magnetic flux will not flow as expected.
Also, when hollow parts are formed in a rotor core, the rotor core tends to be deformed. Therefore, when the rotor core is rotated at a high-speed, there is a likelihood that the rotor core will be deformed due to a centrifugal force generated by the high-speed rotation.